Field of the Invention
The present invention relates to an energy storage module including an energy storage cell group formed by stacking a plurality of energy storage cells in a stacking direction and a pair of end plates provided at both ends of the energy storage cell group in the stacking direction to hold the energy storage cells of the energy storage cell group together.
Description of the Related Art
In general, an energy storage module including an energy storage cell group formed by stacking a plurality of energy storage cells is known. For example, this energy storage module is mounted in an electrically driven vehicle such as a hybrid vehicle or EV. To this end, the high output voltage is achieved by stacking a large number of energy storage cells.
In the energy storage module, a negative (−) electrode terminal of one of the adjacent energy storage cells and a positive (+) electrode terminal of the other of the adjacent energy storage cells are electrically connected in series by a bus bar. An output line is electrically connected to an electrode terminal of an energy storage provided at one end in the stacking direction.
At the output line, it is required to reduce connection resistance, in particular, for outputting a large amount of electrical current. Normally, the connector terminal of the output line is tightened and held by applying a strong tightening torque to the electrode terminal of the energy storage cell. Therefore, since a large rotational torque is applied to the electrode terminal, the electrode terminal may be damaged undesirably.
In this regard, for example, a battery system disclosed in Japanese Laid-Open Patent Publication No. 2010-080353 is known. In this battery system, a battery cell block formed by stacking a plurality of battery cells is fixed in the stacking direction using a pair of end plates.
The output line is connected to the electrode terminal of the battery cell through a relay bus bar, and a connector terminal of the output line is connected to the relay bus bar using a locking screw and a nut. The nut is unrotatably fixed to the end plate. The locking screw is screwed into this nut to connect the relay bus bar and the connector terminal of the output line for fixing the output line to the end plate.